Yes people glance at their phone while walking. Just like drivers glance at their phone while driving (or fiddle with those stupid touch-screens that are ubiquitous now).

But just like there aren't many drivers who would stare intently at their phone while driving through a busy intersection, there aren't many pedestrians that will stare intently at a phone while crossing a busy street. It's simple self-perservation.

Also, phones have been around for ages now. Pedestrians are being hit and killed at a higher rate since the pandemic started, not since the wide adoption of cellphone technology.